Soil temperature determines the reaction of olive cultivars to verticillium dahliae pathotypes

Development of Verticillium wilt in olive, caused by the soil-borne fungus Verticillium dahliae, can be influenced by biotic and environmental factors. In this study we modeled i) the combined effects of biotic factors (i.e., pathotype virulence and cultivar susceptibility) and abiotic factors (i.e., soil temperature) on disease development and ii) the relationship between disease severity and several remote sensing parameters and plant stress indicators. Methodology: Plants of Arbequina and Picual olive cultivars inoculated with isolates of defoliating and non-defoliating V. dahliae pathotypes were grown in soil tanks with a range of soil temperatures from 16 to 32°C. Disease progression was correlated with plant stress parameters (i.e., leaf temperature, steady-state chlorophyll fluorescence, photochemical reflectance index, chlorophyll content, and ethylene production) and plant growth-related parameters (i.e., canopy length and dry weight). Findings: Disease development in plants infected with the defoliating pathotype was faster and more severe in Picual. Models estimated that infection with the defoliating pathotype was promoted by soil temperatures in a range of 16 to 24°C in cv. Picual and of 20 to 24°C in cv. Arbequina. In the non-defoliating pathotype, soil temperatures ranging from 16 to 20°C were estimated to be most favorable for infection. The relationship between stress-related parameters and disease severity determined by multinomial logistic regression and classification trees was able to detect the effects of V. dahliae infection and colonization on water flow that eventually cause water stress. Conclusions: Chlorophyll content, steady-state chlorophyll fluorescence, and leaf temperature were the best indicators for Verticillium wilt detection at early stages of disease development, while ethylene production and photochemical reflectance index were indicators for disease detection at advanced stages. These results provide a better understanding of the differential geographic distribution of V. dahliae pathotypes and to assess the potential effect of climate change on Verticillium wilt development.Financial support for this research was provided by Project P08-AGR-03528 from ‘‘Consejería de Economía, Innovación y Ciencia’’ of Junta de Andalucía and the European Social Fund (JANC), and projects AGL-2012-37521 (JANC) and AGL2012-40053-C03-01 (PJZT) from the Spanish ‘‘Ministerio de Economia y Competitividad’’ and the European Social Fund. R. Calderón is a recipient of research fellowship BES-2010-035511 from the Spanish ‘‘Ministerio de Ciencia e Innovación’’ and C. Lucena was a recipient of a JAE-DOC postdoctoral contract from ‘‘Consejo Superior de Investigaciones Científicas’’ (CSIC) co-funded by the European Social Fund. TPeer Reviewe

Efecto de una cepa de Fusarium oxysporum y de diversas levaduras sobre la nutrición férrica de plantas de pepino y tomate

Trabajo presentado en el XVI Congreso Nacional de Ciencias Hortícolas, celebrado en Córdoba del 17 al 22 de octubre de 2021,El hierro (Fe) es un micronutriente esencial para las plantas. En suelos calizos se encuentra en su forma oxidada (Fe 3+), presentando baja solubilidad y disponibilidad para las plantas. Bajo deficiencia de Fe, las plantas dicotiledóneas inducen diversas respuestas fisiológicas y morfológicas en sus raíces para facilitar así su captación y paliar los efectos que produce su deficiencia. Existen evidencias de que determinados microorganismos rizosféricos, como los que provocan la Respuesta Sistémica Inducida (ISR), pueden facilitar la nutrición férrica de las plantas. El objetivo de este trabajo ha sido, por una parte, estudiar el efecto de la cepa no patogénica de Fusarium oxysporum (FO12), posiblemente inductora de ISR, sobre el crecimiento y clorosis de plantas de tomate (Solanum lycopersicum Mill.), y sobre la colonización de raíces de pepino (Cucumis sativus L.). Por otra parte, estudiar el efecto de determinadas levaduras (Debaryomyces hansenii, Saccharomyces cerevisiae y Hansenula polymorpha) sobre diversas respuestas a la deficiencia de Fe en plantas de pepino. Los experimentos con tomate se han desarrollado en suelo calizo y los de pepino en cultivo hidropónico. Los resultados obtenidos con FO12 han mostrado su capacidad para colonizar endofiticamente las raíces de pepino y su efecto promotor del crecimiento, la concentración de clorofila y de Fe (en hojas) en plantas de tomate. Las diferentes levaduras utilizadas han causado inducción de la capacidad reductora de Fe 3+, de la acidificación de la rizosfera, y de la proliferación de pelos radicales en la zona subapical de las raíces de pepino. Estos resultados sugieren que, tanto FO12 como las diferentes levaduras utilizadas, tienen potencial como biofertilizantes de Fe.Plan Propio de la Universidad de Córdoba y Ministerio de Ciencia e Innovación

High-resolution hyperspectral and thermal imagery acquired from UAV platforms for early detection of Verticillium wilt using fluorescence, temperature and narrow-band índices

Trabajo presentado en el Workshop on UAV-based Remote Sensing Methods for Monitoring Vegetation, celebrado en Colonia (Alemania) el 9 y 10 de septiembre de 2013. Más información en http://www.tr32db.uni-koeln.de/workshops/proceedings.php?wsID=3.Verticillium wilt (VW) caused by the soil-borne fungus Verticillium dahliae Kleb, is the most limiting disease in all traditional olive-growing regions worldwide. This pathogen colonizes the vascular system of plants, blocking water flow and eventually inducing water stress. The present study explored the use of high-resolution thermal imagery, chlorophyll fluorescence, structural and physiological indices (xanthophyll, chlorophyll a+b, carotenoids and B/G/R indices) calculated from multispectral and hyperspectral imagery acquired from a fixed-wing UAV platform as early indicators of water stress caused by VW infection and severity. The study was conducted in two olive orchards naturally infected with V. dahliae. Time series of airborne thermal, multispectral and hyperspectral imagery were conducted with 2-m and 5-m wingspan electric Unmanned Aerial Vehicles (UAVs) operated by the Spanish Laboratory for Research Methods in Quantitative Remote Sensing (Quantalab, IAS-CSIC, Spain) in three consecutive years and related to VW severity at the time of the flights. Concurrently to the airborne campaigns, field measurements conducted at leaf and tree crown levels showed a significant increase in crown temperature (Tc) minus air temperature (Ta) and a decrease in leaf stomatal conductance (G) across VW severity levels, identifying VW-infected trees at early stages of the disease. Higher Tc-Ta and G values measured in the field were associated with higher VW severity levels. At leaf level, the reduction in G caused by VW infection was associated with a significant increase in the Photochemical Reflectance Index (PRI570) and a decrease in chlorophyll fluorescence. The airborne flights enabled the early detection of VW by using canopy-level image-derived airborne Tc-Ta, Crop Water Stress Index (CWSI) calculated from the thermal imagery, blue / green / red ratios (B/BG/BR indices) and chlorophyll fluorescence, confirming the results obtained in the field. Airborne Tc-Ta showed rising temperatures with a significant increase of ~2K at low VW severity levels, and was significantly correlated with G (R2=0.76, P=0.002) and PRI570 (R2=0.51, P=0.032). Early stages of disease development could be differentiated based on CWSI increase as VW developed, obtaining a strong correlation with G (R2=0.83, P<0.001). Likewise, the canopy-level chlorophyll fluorescence dropped at high VW severity levels, showing a significant increase as disease progressed at early VW severity levels. These results demonstrate the feasibility of early detection of V. dahliae infection and discrimination of VW severity levels using remote sensing. Indicators based on crown temperature, CWSI, and visible ratios B/BG/BR as well as fluorescence were effective in detecting VW at early stages of disease development. On affected plants, the structural indices, PRI, chlorophyll and carotenoid indices, and the R/G ratio were good indicators to assess the damage caused by the disease.Peer Reviewe

Proteomic analysis of intestinal mucosa responses to Salmonella enterica serovar typhimurium in naturally infected pig

Salmonella enterica serovar typhimurium (S. typhimurium) is one of the most frequent Salmonella serotypes isolated from European pigs. Despite the advances in understanding the mechanisms involved in host-pathogen interactions and host cell responses to S. typhimurium, the global change that occurs in naturally exposed populations has been poorly characterized. Here, we present a proteomics study on intestinal mucosa of pigs naturally infected with S. typhimurium, in order to better understand the pathogenesis of salmonellosis and the pathways which might be affected after infection. Samples were analyzed by 2D-DIGE and 44 different proteins exhibited statistically significant differences. The data set was analyzed by employing the Ingenuity Pathway Analysis and the physiological function most significantly perturbed were immunological and infectious disease, cellular assembly and organization and metabolism. The pathways implicated in the porcine immune response to S. typhimurium were gluconeogenesis and Rho GDI/RhoA signaling, and our results suggest that keratins and the intermediate filaments could play an important role in the damage of the mucosa and in the success of infection. The role of these findings in salmonellosis has been discussed, as well as the importance of analyzing naturally infected animals to have a complete picture of the infection. Also, we compared the results found in this work with those obtained in a similar study using experimentally infected animals. © 2013 Elsevier Ltd.This research was supported by the Excellence Project of the Junta de Andalucía GovernmentP07-AGR-02672 and by the National R&D Program of the Spanish Ministry of Science and Innovation (AGL2011-28904).Peer Reviewe

Differential effect of soil temperature and Verticillium dahliae pathotypes on development of Verticillium wilt in olive cultivars

Póster presentado en el 6th meeting of the IOBC-WPRS Working Group Multitrophic Interactions in Soil, celebrado en Córdoba (España) del 4 al 7 de abril de 2011.Peer Reviewe

Verticillium dahliae pathotypes and olive cultivars determine geographic distribution and development of Verticillium wilt under current and future climate change scenarios in Southern Spain

Ponencia presentada en el 11 th International Verticillium Symposium, celebrado en Göttingen (Alemania) del 5 al 8 de mayo de 2013.Global climate variability and change caused by natural processes as well as anthropogenic factors are major environmental issues in the 21st century. The increase in mean temperatures, change in precipitation regimes, and a continuous increase in CO2 concentration are likely the main scientific evidence of climate change in recent decades. Plant disease epidemics result from specific interactions of a susceptible host plant, a prevalent and virulent pathogen and a conducive environment. Consequently, shifts in any one of these components can change geographic distribution and disease expression in a given pathosystem. Verticillium wilt (VW) of olive caused by the soil-borne fungus Verticillium dahliae is of major concern for the olive industry in the Mediterranean basin, mainly due to the rapid and wide spread of the highly virulent defoliating (D) pathotype. In this work, we have evaluated the effect of temperature and CO2 concentration on virulence of V. dahliae pathotypes and olive cultivars interactions.Peer Reviewe

Teledetección aerotransportada hiperespectral y térmica de alta resolución para la detección temprana de Verticilosis en olivar usando fluorescencia, temperatura e índices espectrales

Ponencia presentada en el XV Congreso de la Asociación Española de Teledetección celebrado en Torrejón de Ardóz (Madrid) del 22 al 24 de octubre de 2013This paper assesses the use of indicators calculated from high-resolution thermal and hyperspectral imagery which are based on structural and physiological indices related with xanthophyll, chlorophyll a+b, carotenoids concentration and chlorophyll fluorescence for the early detection of stress caused by Verticillium dahliae in olive trees. This study was conducted in two commercial olive orchards where foliar and crown measurements were obtained by punctual sensors and time series of airborne thermal and hyperspectral imagery were acquired using Unmanned Aerial Vehicles (UAV) in three consecutive years and related to Verticillium wilt severity at the time of the flights.Peer Reviewe

First report of southern blight of pepper caused by Sclerotium rolfsii in southern Spain

In May 2009, a stem rot of pepper (Capsicum annuum L.) occurred in a 20-ha field in Hacienda de Tarazona, Seville, in southern Spain. Affected plants appeared singly or were grouped in circular patches as much as 8 to 10 m in diameter.Peer Reviewe

High-resolution airborne hyperspectral and thermal imagery for early detection of Verticillium wilt of olive using fluorescence, temperature and narrow-band spectral indices

Verticillium wilt (VW) caused by the soil-borne fungus Verticillium dahliae Kleb, is the most limiting disease in all traditional olive-growing regions worldwide. This pathogen colonizes the vascular system of plants, blocking water flow and eventually inducing water stress. The present study explored the use of high-resolution thermal imagery, chlorophyll fluorescence, structural and physiological indices (xanthophyll, chlorophyll a+b, carotenoids and blue/green/red B/G/R indices) calculated from multispectral and hyperspectral imagery as early indicators of water stress caused by VW infection and severity. The study was conducted in two olive orchards naturally infected with V. dahliae. Time series of airborne thermal, multispectral and hyperspectral imagery was acquired in three consecutive years and related to VW severity at the time of the flights. Concurrently to the airborne campaigns, field measurements conducted at leaf and tree-crown levels showed a significant increase in crown temperature (Tc) minus air temperature (Ta) and a decrease in leaf stomatal conductance (G) across VW severity levels, identifying VW-infected trees at early stages of the disease. Higher Tc-Ta and G values measured in the field were associated with higher VW severity levels. At leaf level, the reduction in G caused by VW infection was associated with a significant increase in the Photochemical Reflectance Index (PRI570) and a decrease in chlorophyll fluorescence (F). The airborne flights enabled the early detection of VW by using canopy-level image-derived airborne Tc-Ta, Crop Water Stress Index (CWSI) calculated from the thermal imagery, blue/blue-green/blue-red ratios (B/BG/BR indices) and chlorophyll fluorescence, confirming the results obtained in the field. Airborne Tc-Ta showed rising values with a significant increase of ~2K at low VW severity levels, and was significantly correlated with G (R2=0.76, P=0.002) and PRI570 (R2=0.51, P=0.032). Early stages of disease development could be differentiated based on a CWSI increase as VW developed, obtaining a strong correlation with G (R2=0.83, P<0.001). Likewise, the canopy-level chlorophyll fluorescence dropped at high VW severity levels, showing a significant increase as disease progressed. These results indicate the potentials of an early detection of V. dahliae infection and discrimination of VW severity levels using remote sensing. Indicators based on crown temperature such as CWSI, and visible ratios B/BG/BR as well as fluorescence were effective in detecting VW at early stages of disease development. In affected trees, the structural indices PRI, chlorophyll and carotenoid indices, and the R/G ratio were good indicators to assess the damage caused by the disease. © 2013 Elsevier Inc.Financial support from the Spanish Ministry of Education and Science for project AGL2009-13105 and from the Regional Government of Andalusia and the European Social Fund for project P08-AGR-03528 is gratefully acknowledged. R. Calderón is a recipient of research fellowship BES-2010-035511 from the Spanish Ministry of Education and Science.Peer Reviewe